EDMONTON - A 16-year-old boy who fatally shot two officers at an apartment complex one week ago had been apprehended in November under the Mental Health Act and was taken to hospital for assessment, Edmonton police said Thursday.

Police also said the boy's gun was the same weapon used in another shooting days before at a nearby restaurant that left a man injured. Deputy Chief Devin Laforce said a bullet casing recovered from the Pizza Hut was forensically matched to the gun recovered from the apartment, and the teen is a suspect in both cases.

“Both events have been served by robust investigations that have followed all lines of inquiry,” Laforce said. “All tips and other investigative avenues were pursued exhaustively by the investigating teams.”

Investigators are working to trace the origins of the gun and how it came to be in the boy's possession, Laforce said. He said other people could face charges.

“Whoever he got that gun from probably faces some criminal jeopardy,” he said.

The gun has not been linked to any other crimes, Laforce said, and police were not ready to confirm details about the firearm.

The Pizza Hut employee who was shot on March 12 remains in hospital in stable but critical condition, he added.

Constables Brett Ryan, 30, and Travis Jordan, 35, were responding to a family dispute at the apartment complex in the northwestern part of the city on March 16 when they were shot by the teen multiple times.

Police have said the boy also shot and wounded his mother during a struggle for the gun before shooting and killing himself. Laforce said multiple shots were fired at the woman. An autopsy conducted by the Edmonton Medical Examiner on Wednesday confirmed the shooter's cause of death was a single gunshot wound consistent with being self-inflicted. He said no one else fired shots.

The mother remains in hospital. She is unable to speak but has been able to communicate through writing, Laforce said, and police plan to interview her once she is released. He said all families affected by the shooting have been co-operating with police.

Laforce said investigators continue to believe the boy's parents, police dispatch and the responding officers were unaware there was a firearm in the home.

“There are many remaining questions about what took place last Thursday,” he said.

Police said they are investigating the youth's phone and computer. They are also waiting on toxicology results.

Supt. Shane Perka said police could not provide details on the outcome of the youth's mental health assessment nor any other medical information.

“We don't have access to that information at this point but it's certainly things that in the coming days and weeks we will be following up on,” he said.

A spokesperson with Alberta Health Services said any information about what care the boy may have received in hospital could not be publicly released due to privacy rules.

Perka added it is unclear whether Ryan and Jordan knew the teen had been apprehended under the Mental Health Act, although information that police had previously responded to a mental health complaint at the apartment would have been available to them.

Laforce and Perka said police are not releasing the youth's name at this time to maintain the integrity of ongoing investigations, including into the origins of the firearm.

“The premature release of information complicates our efforts,” Perka said. “We also speak in the interests of multiple families whose lives have been irreparably altered by these events.”

This report by The Canadian Press was first published March 23, 2023.

-- With files from Emily Blake in Yellowknife.